1. Field of the Invention
The present invention is related to an improved structure of a contact piece for cable television signals, and especially to such a structure of which the electric characteristic impedance of the contact piece is largely reduced, the propagating rate of the contact piece is increased. The improved structure of a contact piece especially suits a system with characteristic impedance of 750 hm to elevate quality of cable television transmission.
2. Description of the Prior Art
Referring to FIG. 1 and 2 showing the structure of a contact piece of a conventional end connector, the contact piece xe2x80x9cAxe2x80x9d is a member integrally formed, it is comprised mainly of a front piece Al and a rear piece A2 with a connecting portion A3 at the middle of them. The front and the rear pieces A1, A2 are folded into undulated forms at the upper and the lower areas of the connecting portion A3, the connecting portion A3 then is folded at the middle thereof to lap the front piece A1 over the rear piece A2 matchably to form an upper and a lower inserting portion to be inserted into two insulation pipes and a housing to form the conventional cable television end connector.
Such a conventional contact piece xe2x80x9cAxe2x80x9d is more convenient in manufacturing, however, a certain thickness is required for an integrally molded piece, while a medium for transmitting signals has its propagation constant xcex3 decided by its characteristic impedance Zo, and the characteristic impedance of the propagating medium is decided by four parameters including the impedance R, the conductance G, the inductive reactance L and the capacitive reactance C of the transmitting medium. By the fact that:
Zo={square root over (R+jwL/G+jwC)}(w=2xcfx80f),
xcex3={square root over ((R+jwL)(G+jwC))}=xcex1+jxcex2,
wherein,
xcex1 is a scalar quantity called decay constant;
xcex2 is an imaginary quantity called phase shift constant;
xcex1, xcex2 respectively decide the incident loss and the return loss of the transmitting medium system, hence goodness and badness of a contact piece is decided by a conductor itself and the inner chamber of a copper pipe which decide the four parameters R, G, L and C, and in turn decide the propagation constant xcex3 (please refer to the attachment 1). Incident losses and return losses of conventional contact pieces are all inferior, and thereby are undesired.
Therefore, it is the motive of the present invention to eliminate the defects resided in the contact pieces of conventional end connectors, and to provide a contact piece formed by lapping and engaging of two identical and very thin sheets and enveloping the contact piece in a plastic insulating pipe and then placing it with the pipe in a housing of the end connector formed integrally, in this way, manufacturing of the cable television end connector is completed. The very thin sheets of the contact piece can largely reduce the characteristic impedance to thereby increase the propagating rate.
The primary object of the present invention is to provide an improved structure of a contact piece for cable television signals of which the characteristic impedance is largely reduced.
The secondary object of the present invention is to provide an improved structure of a contact piece for cable television signals of which the propagating rate is increased.
To achieve the above stated objects, the present invention is characterized by: the contact piece thereof is formed by lapping and engaging of two identical and very thin sheets and enveloping the contact piece in a plastic insulating pipe and then placing it with the pipe in a housing of the end connector formed integrally, in this way, manufacturing of a cable television end connector is completed. The very thin sheets of the contact piece can largely reduce the characteristic impedance to thereby increase the propagating rate.